Electrical energy may be stored with the aid of batteries. Batteries convert chemical reaction energy into electrical energy. A distinction is made between primary batteries and secondary batteries. Primary batteries are non-rechargeable, while secondary batteries, also referred to as accumulators, are rechargeable. A battery includes one or multiple battery cells.
In particular, so-called lithium-ion battery cells are used in an accumulator. They are characterized, among other features, by high energy densities, thermal stability, and extremely low self-discharge. Lithium-ion battery cells are used, for example, in motor vehicles, in particular in electric vehicles (EVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs).
Lithium-ion battery cells include a positive electrode, also referred to as a cathode, and a negative electrode, also referred to as an anode. The cathode and the anode each include a current collector, to which an active material is applied.
A generic battery is described in German Patent Application No. DE 10 2012 208 321 A1, which includes a cathode whose active material contains a metal oxide and an NCM (Nickel-Cobalt-Manganese) compound. The metal oxide is Li2MnO3, and the NCM compound is LiMO2, M being selected from the elements nickel, cobalt, and manganese.
The active material for the anode is silicon, for example. However, graphite is also widely used as active material for anodes. Lithium atoms are intercalated into the active material of the anode.
During operation of the battery cell, i.e., during a discharging operation, electrons flow in an external circuit from the anode to the cathode. During a discharging operation, lithium ions migrate from the anode to the cathode within the battery cell. In the process, the lithium ions are reversibly deintercalated from the active material of the anode, also referred to as delithiation. During a charging operation of the battery cell, the lithium ions migrate from the cathode to the anode. In the process, the lithium ions are reversibly reintercalated into the active material of the anode, also referred to as lithiation.
The electrodes of the battery cell have a foil-like design and are wound to form an electrode winding, with a separator situated in between which separates the anode from the cathode.
Such an electrode winding is also referred to as a “jelly roll.” The electrodes may also be layered one above the other to form an electrode stack.
The two electrodes of the electrode winding or of the electrode stack are electrically connected via poles of the battery cell, also referred to as terminals. A battery cell generally includes one or multiple electrode windings or electrode stacks. The electrodes and the separator are surrounded by an electrolyte which is generally liquid. The electrolyte is conductive for the lithium ions, and allows transport of the lithium ions between the electrodes.
German Patent Application No. DE 10 2012 831 A1 provides a spinel which is usable as active material for a cathode of a battery cell. The spinel has been doped.
Likewise, U.S. Patent Application Publication No. 2011/0052988 A1 describes an active material for a cathode of a battery cell which has been doped.
In addition, U.S. Pat. No. 4,973,534 describes a cathode for a battery cell whose active material has been doped.
Furthermore, U.S. Pat. No. 6,022,641 A also describes an active material for a cathode of a battery cell which has been doped.